Calling ImageCache in code

Hi,
I know that for calling ImageCache there is function:

print theme('imagecache', 'profile_name', $img_url, 'just a test image', 'test image');

but it does not seam to work for me....
I am trying to link an image to nodes file attachment to get some extra flexibility I am trying to do it in Views adding custom php field. So the code I am using looks like this:

<?php
//Gets nodes attainment`s file path
$node = node_load($data->nid);
$file = upload_load($node);
$file_path = $file[array_shift(array_keys($file))]->filepath;
//Just to make sure it received the data
echo $file_path;
//Checking file path of first attached image (works fine) 
echo $node->field_image_name[0][filepath];
$img_src = $node->field_cover[0][filepath];
//Does not show any results
print theme('imagecache', 'profile name', $img_src, 'just a test image', 'test image');
//Results in a link to attachment file with text of "> may be I missed something?
echo '<a href="'.$file_path.'"><img class="" title="" alt="" src="'.theme("imagecache", "cover", $img_src).'"></a>';
?>

Thanks for help in advance :)